BR112019026532A2 - CURABLE COMPOSITION FOR THE PRODUCTION OF A DENTAL COMPOUND CROWN AND PRODUCTION PROCESS - Google Patents

Abstract

The invention relates to the curable composition for producing dental composite crowns, the composition comprising a resin matrix comprising polymerizable (meth) acrylate (s) that does not comprise (u) a portion of urethane, (meth) acrylate polymerizable urethane (s), wherein the polymerizable (meth) acrylate (s) that do not comprise a portion of urethane are used in excess of the (met) polymerizable urethane acrylate (s), a filler matrix comprising nanoagglomerate (s), pyrolysed silica in an amount below 8% by weight relative to the weight of the entire composition, an initiator system comprising photoinitiator (s), organic dye (s), where the curable composition does not comprise softener in an amount greater than 5% by weight relative to the total weight of the composition, the curable composition having a viscosity below 150 Pa.sa 23 ° C and a shear rate of 1 s-1. The invention also relates to a cured article obtained by radiation curing of this curable composition using an additive manufacturing method.

Description

“CURABLE COMPOSITION FOR THE PRODUCTION OF A DENTAL COMPOUND CROWN AND PRODUCTION PROCESS” Field of the invention

[001] The invention relates to a curable composition suitable for the production of dental composite crowns, a prefabricated dental composite crown and a process for producing such a dental composite crown by an additive manufacturing technique.

Background

[002] For the treatment of dental defects, a variety of different solutions are available on the market. In general, dental diseases can be treated by restoration methods or prosthetic methods. Direct restoration composites are, for example, highly loaded materials that are characterized by excellent mechanical properties and low wear.

Unfortunately, due to the high filling load, these materials tend to be brittle.

[003] On the other hand, temporary crown and bridge materials used as a prosthetic material have a lower filling content. This results in better elasticity and greater resistance to fracture, but is often accompanied by increased wear, which prevents the long-term use of these materials. For manufacturing in the office or clinic of indirect composite restorations, there is a need for a material that combines the properties of the materials described above. Prosthetic methods are typically used if there is not enough remaining dental structure to allow a restoration treatment, for example, filling a cavity with a dental filling material. Prosthetic treatment usually begins with obtaining a dental impression of the dental situation in the patient's mouth. The obtained record represents the status as it is.

[004] In a next step, the tooth to be treated is additionally prepared, that is, the tooth is formatted with a shape that later allows the fixation of an artificial crown. The artificial crown is typically designed from information obtained from the dental impression and the shape of the treated tooth.

In a next step, the artificial crown is produced in a dental laboratory and specifically designed for this individual case. This procedure takes time and is expensive.

[005] If, however, a quick and inexpensive prosthetic treatment is desired, the practitioner may consider using preformed crowns instead. This type of treatment is often used in pediatric dentistry. Different types of prefabricated crowns are currently available on the market for this purpose.

[006] A popular solution is the use of stainless steel crowns (for example, with 3M Oral Care; 3M ESPE). Stainless steel crowns are easy to manufacture and are also durable over years.

[007] Preformed crowns made of stainless steel have, in addition, the benefit of being pre-trimmed, turned and crimped for quick and easy positioning. Due to the so-called “snap-fit feature”, the stainless steel crown is readily retained and fits over the prepared tooth outline.

[008] However, due to their metallic surface, the stainless steel crowns do not meet the desired aesthetic requirements. To remedy this defect, coated stainless steel crowns have been suggested.

[009] However, coated stainless steel crowns show only limited flexibility due to the stiffer walls, at least in some areas of the crown. In addition, shattering of the lining of these crowns is reported, and a metallic sheen of the underlying stainless steel crown detracts from the aesthetic appearance. Thus, it was suggested to try to manufacture preformed crowns from other materials. Zirconia ceramic (ZrO2) is quite common for crowns designed individually for cosmetic dentistry.

[010] ZrO2 has some exclusive material properties, for example, high strength and robustness, translucency, tintability and biological compatibility, which makes it well suited for crowns or even bridges.

[011] However, due to the material's properties, the side walls of these crowns are not flexible and therefore no recess design is possible.

In addition, compared to stainless steel crowns, a different and more invasive tooth preparation is required without or with a very limited possibility of recess retention, which again leads to a more careful cementation technique. It has also been suggested to manufacture preformed crowns from polymeric materials.

[012] On this subject, US patent 8,651,867 B2 (Zilberman) describes a dental crown configured to be readily assembled in a patient's mouth as part of a treatment of primary teeth and permanent molars, the dental crown having a natural appearance and the color of a vital tooth, and consists of a layer of thermoplastic material configured to define a tooth-shaped upper surface and flexible side surfaces.

[013] As suitable thermoplastic materials, polymers selected from polyacetal, polyacrylate, polymethacrylate (PMMA), poly (aryl ether ketone) (PAEK), poly (ether ketone) (PEK), poly (ether ether ketone) ( PEEK), poly (imide ether) (PEI), poly (sulfone ether) (PES) and polysulfone (PSU).

[014] US patent 2004/0161726 A1 (Saito et al.) Describes a crown prosthesis that has a wear resistance and an aesthetic property that comprises a polymer from a mixture of a polymerizable compound with an unsaturated double bond, a filler and a polymerization initiator, with an external shape that resembles a tooth and a space to be filled with a dental composite resin between an internal surface of the same and a contiguous tooth.

[015] However, the workflow required for applying preformed crowns based on polymeric material does not really differ from the workflow required for applying preformed zirconia crowns, even if a more flexible material is used .

[016] Commercially available polymer-based preformed anchors typically have wall thicknesses of more than 500 µm, which gives them insufficient flexibility and therefore no recess design options as an additional support for cementation.

[017] The fact that the properties of the material do not allow thinner walls makes the walls a limiting factor for design options.

[018] However, to ensure sufficient adhesive attachment of these crowns to a prepared dental surface, adhesive cementation is recommended or necessary. This makes the entire prosthetic procedure more complicated and expensive. In general, for crowns and bridges, different carburizing techniques are available.

[019] These can be divided into groupings such as temporary carburizing (for example, 3M Oral Care RelyX ™ TempNE / E; 3M ESPE), conventional carburizing (for example, 3M Oral Care Ketac ™ CEM or Ketac ™ CEM Plus; 3M ESPE), self-adhesive cementation resin (eg 3M Oral Care RelyX ™ Unicem; 3M ESPE), self-adhesive cementation resin (eg 3M Oral Care RelyX ™ Ultimate; 3M ESPE).

[020] In general, carburization needs to be long-lasting over the life of the indication, which could be achieved due to chemical bonding or mechanical retention, or a combination of them.

[021] The choice of the cement used or the general cementation technique for a specific indication is therefore influenced by the material of the restoration, by the indication itself, by the preparation technique, but also the cost and aesthetics play a role.

[022] For a quick and easy office workflow with preformed crowns, for example, pediatric dentistry, a quick and easy carburizing technique is not only desired, but also necessary.

[023] For this reason, conventional cementation techniques are used for fixing stainless steel crowns. These cementos not only have an easier workflow, but are also cheaper than self-adhesive resin or adhesive resin cement. In addition, they are more tolerant to moisture and more robust against blood and saliva than self-adhesive or adhesive cementos.

[024] This technique is dominant in pediatric dentistry due to the time-saving workflow in the office and the fact that an individually designed crown is not necessarily required.

[025] Patent document WO 2007/098485 A2 (Nusmile) describes a preformed dental crown with a central surface, a circumferential surface in transition from and integral with the central surface, the circumferential surface including a tapering towards the gingival end and said taper having a thickness in the range of 0 to 0.5 mm at a gingival end of at least 1.0 mm adjacent to the transition to the central surface.

[026] WO 2008/033758 A2 (3M) describes a solid dental crown that includes a solid, self-sustaining pre-hardened dental crown that has an external crown shape defined by an external crown shape defined by a crown surface external.

[027] US patent 2007/0196792 A1 (Johnson et al.) Describes a prefabricated dental crown that is tooth-colored and has a recess. The materials that are considered useful for the manufacture of the prefabricated dental crown are thermoplastic resins, such as polyacetal, polyacrylate, polyamide, poly (aryl ether ketone), poly (ether-ether-ketone) (PEEK), poly (ether-imide ), etc.

[028] WO 2013/153183 (IvoclarVivadent) describes the use of a composite resin composition containing: (a) at least one reactive polyglutinant, (b) a first photopolymerization initiator with maximum absorption at a wavelength 400 nm or less, (c) a second light curing initiator with a maximum absorption at a wavelength of 400 nm and (d) an absorbent with a maximum absorption at a wavelength less than 400 nm for production stereolithography of a component formed dental based on composite resin.

[029] US 2014/131908 (Dentsply) describes a composition for the manufacture of a three-dimensional dental prosthesis that comprises a mixture of 1 to 99.5% monomer, 5 to 99% of at least one (meth) acrylate mono or multifunctional, from 0 to 60% of at least one inorganic filler, from 0 to 60% of at least one organic filler, from 5 to 10% of an acrylic and silicone based rubber impact modifier, from 0 to 10 % pigments and 0.01 to 10% photoinitiators.

[030] US 8,329,776 (Hecht et al) describes hardenable dental compositions comprising (meth) urethane acrylates, (meth) acrylates, different types of fillers and initiator.

[031] WO 2015/006087 A1 (3M) describes a hardenable dental composition comprising aggregated nanoparticles, agglomerated nanoparticles, (meth) acrylates, (meth) urethane acrylates and a redox curing initiator system.

[032] The hardenable dental compositions described in the document US

8,329,776 and WO 2015/006087 are typically supplied as a kit of parts comprising a base paste and a catalyst paste. The hardenable compositions can be used in particular for the production of artificial crowns and bridges for temporary or long-term use.

[033] US 2013/0210959 (Yang et al.) Describes curable dental compositions comprising a resin system comprising a semicrystalline resin polymerizable via free radicals having a molecular weight of not more than 2000 g / mol and at least 50% in filling weight of nano-clusters. According to one embodiment, the composition is provided as a preformed dental crown in the form of a self-supporting hardenable structure that has a first shape and sufficient malleability to be formed into a second shape. Molding can be done, for example, by extrusion, injection molding, pressing and calendering.

[034] US 2016/0136059 A1 (Hecht et al.) Refers to dental compositions that comprise a filling with non-sized aggregate particles and a filling that comprises agglomerated nanoparticles, (meth) urethane acrylates, (meth) acrylates and a redox curing initiator system.

[035] US 2014/0131908 A1 (Sun et al.) Refers to a system of printable polymerizable material containing an acrylic and silicone based rubber impact modifier to produce, for example, artificial teeth. The polymerizable material system can contain filling in an amount from 0 to 75% by weight. In the examples section, compositions containing filler in an amount of more than 55% by weight are described.

[036] US 2015/0111176 A1 Wachter et al.) Refers to the use of a composite resin composition comprising a polyreactive binder, a first photopolymerization initiator, a second photopolymerization initiator and an absorbent for the stereolithographic production of a shaped part based on composite resin. The resin composition also comprises a filler. A filling amount in the range of 50 to 80% by weight is considered preferable. As examples, compositions are provided containing a mixture of Bis-GMA and UDMA in combination with a filling content of more than 60% by weight. However, none of the solutions suggested in the prior art is completely satisfactory.

[037] All of these types of crowns have disadvantages in different aspects, mainly related to a more complex and time-consuming workflow, but also due to durability and / or aesthetics.

Description of the invention

[038] There is a desire for prefabricated composite crowns showing basically the same performance as temporary crowns obtained from commercially available paste materials (eg Protemp ™ 4; 3M Oral Care) which, however, are beyond autoclavable.

[039] Before a particular preformed dental composite crown is finally attached to the surface of a prepared tooth, it is generally necessary to test various sizes or shapes of different preformed dental composite crowns in a patient's mouth.

[040] After the testing process, the remaining preformed dental composite crowns are contaminated and therefore need to be autoclaved before they can be reused.

[041] Autoclaving conditions typically include heating the article in a humid atmosphere for at least 15 min at a temperature of at least 120 ° C. During this process, composite articles containing a redox initiator system typically tend to become brittle.

[042] Ideally, the desired prefabricated composite crown should have essentially the same performance before and after an autoclaving process is carried out and the respective mechanical values (such as module E) should not differ, for example, from more than about +/- 10% compared to the original value.

[043] Ideally, prefabricated composite crowns should show a so-called “locking effect” comparable to stainless steel crowns.

[044] Additionally, prefabricated composite crowns must be easy to manufacture, that is, it should be possible to efficiently produce a sufficient volume of crowns.

[045] One or more of the above objectives is achieved by the invention described in this text and in the claims.

[046] One or more of the above objectives is achieved by the invention described in this text and in the claims. a resin matrix comprising: polymerizable (meth) acrylate (s) that do not comprise a portion of urethane, polymerizable urethane (meth) acrylate (s), the (meth) acrylate polymerizable (s) that does not comprise a portion of urethane is / are used in excess of the polymerizable urethane (meth) acrylate (s), a filler matrix comprising: nanoaggregation (s), optionally pyrolysed silica, preferably in an amount below 8% by weight, the filler matrix being preferably present in an amount of 5 to 45% by weight an initiator system comprising: photoinitiator ( (s), organic dye (s), the curable composition that does not comprise softener in an amount greater than 5% by weight,

where% by weight is related to the total weight of the composition, the curable composition having a viscosity below 150 Pa.s at 23 ° C and a shear rate of 1 s-1.

[047] The invention also relates to a dental composite crown obtained by curing the curable composition, as described in the present text and in the claims.

[048] The invention also relates to a process for the production of dental composite crowns with an additive manufacturing technique, as described in the present text and the claims.

[049] The invention also relates to a kit of parts comprising at least two different dental composite crowns, as described in the present text and in the claims.

[050] Unless otherwise defined, for this description the following terms will have the designated meaning:

[051] A "curable material or component" or "polymerizable component" is any component that can be cured or solidified by radiation-induced polymerization or crosslinking. A hardenable component can contain only one, two, three or more polymerizable groups. Typical examples of polymerizable groups include unsaturated carbon groups, such as a vinyl group present, that is, in a (methyl) acrylate group.

[052] A "photoinitiator" is a substance capable of initiating the curing process of a polymerizable composition upon exposure to radiation (for example, with a wavelength of 350 to 600 nm or 350 to 420 nm).

[053] A "monomer" is any chemical substance that can be characterized by a chemical formula, which has polymerizable groups (including (meth) acrylate groups) that can be polymerized into oligomers or polymers, thereby increasing molecular weight. The molecular weight of monomers can usually and simply be calculated based on the given chemical formula.

[054] As used in the present invention, the term "(meth) acryl" is an abbreviation that refers to "acryl" and / or "methacryl". For example, a “(meth) acryloxy” group is an abbreviation that refers to an acryloxy group (that is, CH2 = CH-C (O) -O-) and / or a methacryloxy group (that is, CH2 = C (CH3) -C (O) -O-).

[055] The terms "curing, hardening or solidification reaction" are used interchangeably and refer to a reaction in which the physical properties, such as viscosity and hardness, of a composition, change over time due to a chemical reaction between individual components. A "urethane group" is a group that has the "-NH-CO-O-" structure.

[056] The term "dental or orthodontic article" means any article that is intended for use in the dental or orthodontic field, especially for the production of a dental restoration, orthodontic devices, a tooth model and parts thereof.

[057] Examples of dental articles include crowns, bridges, fillings, restorations, veneers, coatings, coverings, crown and bridge structures, implants, abutments, dental grinding blocks, monolithic dental restorations and parts thereof.

[058] Examples of orthodontic articles include brackets, mouth tubes, handles and buttons and parts thereof.

[059] A dental or orthodontic article must not contain components that are harmful to the patient's health and, therefore, it must be free of dangerous and toxic components that may migrate out of the dental or orthodontic article. The surface of a tooth is not considered a dental or orthodontic article.

[060] "Glass" means an inorganic non-metallic amorphous material that is thermodynamically a sub-cooled and frozen melt material. Glass refers to a transparent, brittle and hard solid. Typical examples include soda-lime glass and borosilicate glass. A glass is an inorganic fusion product, which has been cooled to a rigid condition without crystallizing. Most glasses contain silica as their main component, as well as a certain amount of glass former. The material or article described in this text does not typically contain a glass.

[061] “Vitroceramics” means an inorganic non-metallic material in which one or more crystalline phases are surrounded by a vitreous phase, so that the material comprises a glass material and a ceramic material in a combination or mixture. Thus, a glass ceramic is a material that shares many properties with glass and the most traditional crystalline ceramics. It is formed like glass and then undergoes heat treatment to partially crystallize. The term glass-ceramics can refer to a mixture of oxides of lithium, silicon and aluminum.

[062] A "powder" means a dry bulk material composed of a large amount of fine particles that can flow freely when agitated or tilted.

[063] A "particle" means a substance that is a solid with a shape that can be geometrically determined. The shape can be regular or irregular.

Particles can typically be analyzed for, for example, particle size and particle size distribution. A particle can comprise one or more crystallites. In this way, a particle can comprise one or more crystalline phases.

[064] The term "associated" refers to a grouping of two or more primary particles that are aggregated and / or agglomerated.

[065] Similarly, the term "unassociated" refers to two or more primary particles that are free or substantially free of aggregation and / or agglomeration.

[066] "Aggregate", as used in the present invention, is the description of a strong association of particles often linked to each other through, for example, residual chemical treatment or partial sintering. The specific surface of the aggregate particles is typically smaller than the specific surface of the primary particles that make up the aggregate (cf. DIN 53206; 1972).

[067] Additional decomposition of the aggregates into smaller entities can occur during a polishing step applied to the surface of a composition containing the aggregate filler but not during the dispersion of the aggregated particles in a resin.

[068] Aggregate fillers and processes for their production and surface treatment are described, for example, in WO 01/30304 and in US patent 6,730,156 (3M). The content of these references is hereby incorporated by reference.

[069] "Agglomerate" is the description of a weak association of particles normally held together through charge or polarity and that can be broken up into smaller entities.

[070] Agglomerated fillers are available for sale, for example, from Degussa, Cabot Corp. or Wacker, under the product designation Aerosil ™, CAB-O-SIL ™ and HDK.

[071] A “non-agglomerated filler” means that the filler particles are present in the resin at an unassociated and distinct stage (ie, non-agglomerated and non-aggregated). If desired, this can be verified by TEM microscopy.

[072] Non-agglomerated, nanodimensioned silicas are commercially available, for example, from Nalco Chemical Co., Naperville, IL., USA, under the trade name “NALCO COLLOIDAL SILICA”, for example, as products

NALCO # 1040, 1042, 1050, 1060, 2327 and 2329.

[073] Non-agglomerated fillers are used and described, for example, in EP 2 167 013 B1 (3M). The content of that reference is hereby incorporated by reference.

[074] The term "primary particle size" refers to the size of a single unassociated crystalline zirconia particle that is considered to be a primary particle. X-ray diffraction (XRD) is typically used to measure primary particle size.

[075] The average particle size of a powder can be obtained from the cumulative grain size distribution curve and is defined as the arithmetic mean of the measured grain sizes of a certain powder mixture. The respective measurements can be made using granulometers available for sale (for example, the CILAS Laser Diffraction Particle Size Analysis Instrument (laser diffraction particle size analyzer)).

[076] A “nano-filling” is a filling, the individual particles of which have a size in the nanometer region, for example, an average particle diameter less than about 200 nm or less than about 100 nm or less than about 50 nm. Useful examples are presented in US 6,899,948 / Zhang et al.) And US 6,572,693 (Wu et al.). The content in relation to silica nanoparticles is hereby incorporated by reference.

[077] The measurement of the size of the nanoparticles is preferably based on a TEM (transmission electron microscopy) method, by which a population is analyzed to obtain an average particle diameter. A preferred method for measuring the particle diameter can be described as follows:

[078] Samples with a thickness not exceeding 80 nm are placed on 200 mesh copper grids with carbon stabilized substrates (SPI Supplies - a division of Structure Probe, Inc., West Chester, PA, USA) . A transmission electron micrograph (TEM, "transmission electron micrograph") is made using JEOL 200CX (JEOL, Ltd. from Akishima, Japan and sold by JEOL USA, Inc.) at 200 Kv. A population size of about 50 to 100 particles can be measured and an average diameter determined.

[079] “Additive manufacturing” means processes used to produce three-dimensional articles. An example of an additive manufacturing technique is stereolithography (SLA) in which successive layers of material are deposited under computer control and are subsequently cured by radiation. Articles can have almost any shape or geometry and are produced from a three-dimensional model or from another source of electronic data. Other examples of additive manufacturing processes or techniques include 3D printing.

[080] The term "resin-modified glass ionomer cement" means a hardenable dental material comprising acid-reactive glass, polyacid, water, polymerizable components and initiator. Resin-modified glass ionomer cement undergoes a double curing reaction, a glass ionomer acid-base cement reaction and monomer polymerization typically based on acrylate (methacrylate).

[081] The term "adhesive resin cement" means a hardenable dental material that cures by radical polymerization of polymerizable components (but not by a glass ionomer cement reaction). An adhesive resin cement requires pre-treatment of hard dental surfaces to effect adhesion.

Unlike resin-modified glass ionomer cement, an adhesive resin cement does not contain added water.

[082] A “self-adhesive resin cement” is an adhesive resin cement that, in addition, contains acidic components and therefore does not require a pre-

treatment of hard dental surfaces to effect adhesion.

[083] In contrast to resin-modified glass ionomer cement, adhesive resin cement and self-adhesive resin cement typically cure only through the polymerization reaction.

[084] "Density" means the ratio of an object's mass and volume. The density unit is typically g / cm3. The density of an object can be calculated, for example, by determining its volume (for example, by calculating or applying the Archimedes principle or method) and by measuring its mass.

[085] The volume of a sample can be determined based on the general external dimensions of the sample. The sample density can be calculated by measuring the sample volume and the sample mass. The total volume of a sample of material can be calculated from the mass of the sample and the density of the material used. The total volume of cells in the sample is assumed to be the remainder of the sample volume (100% less the total volume of material).

[086] A material or composition is "essentially or substantially free of" a particular component in the meaning of the invention if the material or composition does not contain said component as an essential feature. Therefore, said component is not intentionally added to the composition or material as such or in combination with other components or ingredients of other components. A composition or material being essentially free of a certain component normally contains the component in an amount less than about 1% by weight or less than about 0.1% by weight or less than 0.01% by weight (or less than 0.05 mol / l solvent or less than 0.005 mol / l solvent or less than 0.0005 mol / l solvent) with respect to the entire material or composition. Ideally, the composition or material does not contain said component. However, sometimes the presence of a small amount of said component is not preventable, for example, due to impurities.

[087] "Ambient conditions" means the conditions to which the composition of the invention is usually subject during storage and handling. Ambient conditions can be, for example, a pressure of 900 to 1100 mbar (90.0 to 110.0 kPa), a temperature of -10 to 60 ° C and a relative humidity of 10 to 100%. In the laboratory, ambient conditions are adjusted up to about 23 ° C and about 1013 mbar (101.3 kPa). In the orthodontic and dental field, ambient conditions are reasonably understood as pressure of 950 to 1050 mbar (95.0 to 105.0 kPa), temperature of 15 to 40 ° C and relative humidity of 20 to 80%.

[088] As used in the present invention, "one", "one", "o", "a", "at least one", "at least one", "one or more" and "one or more" are used interchangeably. The terms "understand" or "contain", and variations thereof, do not have a limiting meaning when those terms appear in the description and claims. As also used in the present invention, the mention of numerical ranges with extremes includes all numbers contained in that range (for example, from 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.).

[089] Adding an “(s)” to a term means that the term must include the singular and plural form. For example, the term "additives (s)" means an additive and more additives (for example, 2, 3, 4, etc.).

[090] Except where otherwise noted, all numbers that express quantities of ingredients, measurement of physical properties, as described below and so on, used in the specification and in the claims, should be understood as being modified in all instances by term “about”.

The term "comprises" will also include the terms "consists essentially of" and "consists of".

Detailed Description

[091] The invention described in this text is advantageous for a number of reasons.

The curable composition described in this text can be easily processed as a building material in an additive manufacturing process that comprises a radiation step, in particular, using a stereolithography technique (SLA technique).

[092] Without wishing to stick to a certain theory, it is believed that the viscosity of the curable composition contributes to an easy processing of the composition in an additive manufacturing technique.

[093] This also allows for the simultaneous production of more individualized composite crowns.

[094] Additionally, without sticking to a specific theory, it is believed that due to the limited quantity or even the absence of softeners, the cured composition becomes better autoclavable.

[095] Softeners are typically present in the curable composition for use as temporary crown and bridge materials that are supplied as a kit of parts comprising a base paste and a catalyst paste. These softeners can migrate out of the cured composite article during an autoclave process.

[096] Since the curable composition described in this text does not typically contain a softener or contains it only in small quantities, the risk of softeners migrating out of the cured composition during an autoclaving process is reduced.

[097] However, the mechanical properties of the cured composition have been found to remain reasonably unchanged after an autoclaving has been performed.

[098] Additionally, the printed article obtained often shows fewer defects and inhomogeneity compared to articles obtained by curing a curable composition containing a redox initiator, which was supplied by mixing a catalyst and base paste manually or by using a static mixing tip.

[099] The curable composition described in this text makes it possible to produce 3-dimensional articles or products with precise construction features and smooth surfaces.

[0100] It was also found that the curable composition described in this text allows the production of three-dimensional structures with wall thicknesses less than 0.8 mm.

[0101] In addition, the curable composition described in this text allows the production of prefabricated composite crowns with the desired “fit effect” comparable to stainless steel crowns.

[0102] Thus, the article obtained after processing the curable composition as a building material in an additive manufacturing process is characterized by a combination of specific properties, such as high mechanical strength, high fracture resistance and superior appearance.

[0103] The curable composition is, in particular, useful in the dental and orthodontic fields and can also facilitate the production in the office of indirect dental restorations on the same day.

[0104] Examples of such indirect dental restorations include dental crowns and bridges, in particular preformed dental composite crowns with a shape that has a recessed structure.

[0105] This shape provides the crown with a so-called “fitting effect” and allows easy positioning of the preformed composite crown on the surface of a prepared tooth, particularly in the pediatric field.

[0106] In certain modalities, the curable composition meets one or more, and sometimes all of the properties mentioned below:

a) it is curable by radiation, having a wavelength in the range of 350 to 600 nm or 350 to 420 nm; b) has a viscosity of: 1 to 100 Pa.s at 23 ° C at a shear rate of 1 s-1; c) has a pH value: from 6 to 8, if placed in contact with wet pH sensitive paper.

[0107] If desired, properties can be measured as described in the examples section.

[0108] In certain modalities, the combination of the following characteristics is sometimes desirable: a) and b), or a), b) and c).

[0109] The curable composition described in this text is radiation curable at a wavelength that is typically used in commercially available additive manufacturing equipment.

[0110] Additionally, the curable composition described in this text typically has a viscosity that allows the composition to be processed in an SLA process. Lower viscosity often allows for better print quality, especially with regard to surface accuracy.

[0111] The curable composition described in this text is typically opaque.

[0112] Since the curable composition typically does not contain acidic components, the pH value of the composition is in the neutral range.

[0113] The curable composition described in this text comprises a resin matrix.

[0114] The resin matrix typically comprises 40 to 90% by weight or 50 to 80% by weight of the curable composition.

[0115] The resin matrix comprises polymerizable (meth) acrylate (s) that does not comprise a portion of urethane as component (A) and polymerizable urethane (meth) acrylate (s) as component (B).

[0116] The resin of the curable composition also comprises (meth) acrylate (s) with at least 1 or 2 polymerizable portions, but which does not comprise (m) a portion of urethane.

[0117] The (meth) acrylate (s) is (are) different from the (meth) urethane acrylate, for example, with respect to functionality, chemical moieties, molecular weight or combinations thereof.

[0118] If desired, the chemical composition can comprise at least two, three or four different types of (meth) acrylate (s).

[0119] The addition of a (meth) acrylate to the resin composition helps to further improve the mechanical properties of the resin composition in its cured stage, in particular with respect to flexural strength or abrasion resistance.

[0120] The molecular weight of the (meth) acrylate (s) is typically at least 170, or at least 200, or at least 300 g / mol.

[0121] The molecular weight of the (meth) acrylate (s) is typically in the range of 170 to 3,000, or 200 to 2,500, or 300 to 2,000 g / mol.

[0122] The (meth) acrylate (s) has (have) radically free active functional groups and includes (in) monomers, oligomers and polymers with two or more ethylenically unsaturated groups.

[0123] Such free radical polymerizable materials include di- or polyacrylates and methacrylates such as glycerol diacrylate, glycerol triacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, 1,3-dianethylacrylate, 1,3-dianethylacrylate 1,3-propanyl dihydrate -propanediol, trimethylolpropane triacrylate, 1,2,4-butanotriol trimethacrylate, 1,4-cyclohexanediol diacrylate, pentaerythritol triacrylate, pentaerythritol tetracrylate, pentaerythritol tetra-acrylate [hexacrylate] acryloxy)] - p-ethoxyphenyldimethylmethane, bis [1- (3-acryloxy-2-hydroxy)] - p-propoxyphenyldimethylmethane; polyethylene glycols bis-acrylates and bis-methacrylates of molecular weight 200-500, copolymerizable mixtures of acrylated monomers such as those of US 4,652,274, and acrylated oligomers such as those of US 4,642,126; and vinyl compounds such as diallyl phthalate, divinyl succinate, divinyl adipate and divinyl phthalate.

[0124] Preferred ethylenically unsaturated monomers are methacrylate and acrylate monomers, such as propanediol di (meth) acrylates, butanediol, hexanediol, octanediol, nonanediol, decanediol and eicosanediol, ethylene glycol di (meth) acrylates, polyethylene and polyethylene diols ethoxylated (meth) bisphenol A acrylates, for example, 2,2'-bis (4- (meth) acryloxytetraethoxyphenyl) propanes and (meth) acrylamides. The monomers used can additionally be esters of [alpha] -cyanoacrylic acid, crotonic acid, cinnamic acid and ascorbic acid.

[0125] It is also possible to use the methacrylic esters mentioned in EP 0 235 826 A1 (ESPE), such as bis [3 [4] -methacryl-oxymethyl-8 (9) - tricycle [5.2.1.02,6] decylmethyl triglycolate. Particularly suitable are 2,2-bis-4 (3-methacryloxy-2-hydroxypropoxy) phenylpropane (Bis-GMA), 2,2-bis-4 (3-methacryloxypropoxy) phenylpropane, triethylene glycol dimethacrylate (TEGDMA) and di (meth) ) bis-hydroxymethyltricyclo- (5.2.1.02,6) decane acrylates.

[0126] It has been found that the use of (meth) acrylate (s) and, more particularly, of the components described above, can be beneficial in providing the hardened composition with sufficient mechanical strength since it can function as a type of agent crosslinking agent useful to improve the mechanical properties of the cured dental composition.

[0127] The (meth) acrylates are / are typically present in the following amounts: - lesser quantity: at least 40 or at least 45 or at least 50% by weight; - higher quantity: maximum of 85 or maximum of 80 or maximum of 70% by weight;

- range: 40 to 85 or 45 to 80 or 50 to 70% by weight; % by weight with respect to the weight of the polymerizable composition.

[0128] Polymerizable (meth) acrylate (s) not containing a portion of urethane are used in excess compared to polymerizable urethane (meth) acrylate (s).

[0129] It was found that the following reason is adequate:

[0130] [polymerizable (meth) acrylates that do not contain a urethane portion] / [polymerizable urethane acrylate (s)] from 5: 1 to 1.5: 1.

[0131] The curable composition comprises at least one, two, three or four different types of urethane (meth) acrylate (s).

[0132] The addition of urethane (meth) acrylate (s) to the resin matrix has been found to contribute to optimize certain mechanical properties such as module E and the fracture work of the cured composition. The molecular weight of urethane (meth) acrylate is typically at least 450, or at least 800 or at least

1,000 g / mol. Useful ranges include 450 to 3,000 or 800 to 2,700 or 1,000 to

2,500 g / mol.

[0133] Molecules that have a molecular weight above about 450 g / mol or about 1,000 g / mol are usually less volatile than molecules that have a lower molecular weight and, therefore, can contribute to supply a biocompatible composition.

[0134] In addition, a sufficiently high molecular weight of urethane (meth) acrylate can contribute to the desired fracture work of the composition after hardening.

[0135] The nature and structure of urethane (meth) acrylate are not particularly limited, unless the desired result cannot be obtained.

[0136] Urethane (meth) acrylates can be obtained by various processes known to the person skilled in the art.

[0137] The urethane (meth) acrylate (s) used in the composition is (are) typically obtained by reacting an NCO-terminated compound with a suitable monofunctional (meth) acrylate monomer, such as hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, preferably hydroxyethyl and hydroxypropyl methacrylate.

[0138] For example, a polyisocyanate and a polyol can be reacted to form an isocyanate-terminated urethane prepolymer which is subsequently reacted with a (meth) acrylate, such as 2-hydroxyethyl (meth) acrylate. These types of reactions can be carried out at room temperature or at higher temperatures, optionally in the presence of catalysts, such as tin catalysts, tertiary amines and the like.

[0139] The polyisocyanates that can be used to form the isocyanate-functionalized urethane prepolymers can be any organic isocyanate having at least two free isocyanate groups. Aliphatic, cycloaliphatic, aromatic and araliphatic isocyanates are included.

[0140] Any of the known polyisocyanates, such as alkyl and alkylene polyisocyanates, cycloalkyl and cycloalkylene polyisocyanates and combinations such as alkylene and cycloalkylene polyisocyanates can be used.

[0141] Preferably, diisocyanates with the formula X (NCO) 2 are used, where X represents an aliphatic hydrocarbon radical with 2 to 12 carbon atoms, a cycloaliphatic hydrocarbon radical with 5 to 18 carbon atoms, a radical aromatic hydrocarbon with 6 to 16 carbon atoms and / or an araliphatic hydrocarbon radical with 7 to 15 carbon atoms.

[0142] Examples of suitable polyisocyanates include 2,2,4-trimethylhexamethylene-1,6-diisocyanate, hexamethylene-1,6-diisocyanate (HDI), cyclohexyl-1,4-di -isocyanate, 4,4'methylene-bis (cyclohexylisocyanate), 1,1'-methylenebis (4-isocyanate) cyclohexane, isophorone diisocyanate, 4,4'-methylene diphenyl diisocyanate, 1 , 4-

tetramethylene diisocicanate, meta- and para-tetramethylxylene diisocicanate, 1,4-phenylene diisocicanate, 2,6-and 2,4-toluene diisocicanate, 1,5-naphthylene diisocyanate, 2,4 ′ And 4,4′- diphenylmethane diisocicanate and mixtures thereof.

[0143] It is also possible to use higher functional polyisocyanates known from the chemistry of polyurethanes or other modified polyisocyanates, for example, containing carbodiimide groups, allophanate groups, isocyanurate groups and / or biuret groups. Particularly preferred isocyanates are isophorone diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate and higher functional polyisocyanates with isocyanurate structure.

[0144] The isocyanate-terminated urethane compound is terminated with a (meth) acrylate to produce a urethane (meth) acrylate compound. In general, any blocking agent of the (meth) acrylate type having a terminal hydroxyl group and also having an acrylic or methacrylic moiety can be used, preferably the methacrylic moiety.

[0145] Examples of suitable blocking agents include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, glycerol di (meth) acrylate and / or trimethylolpropane di (meth) acrylate. Particularly preferred are 2-hydroxyethyl methacrylate (HEMA) and 2-hydroxyethyl acrylate (HEA).

[0146] The equivalent ratio between isocyanate groups and reactive compounds vis-à-vis isocyanate groups is 1.1: 1 to 8: 1, preferably 1.5: 1 to 4: 1.

[0147] The polyaddition reaction of isocyanate can take place in the presence of catalysts known from polyurethane chemistry, for example, organotin compounds, such as benzyl tin or amine dilaurate catalysts, such as diazabicyclo [2.2.2] octane. In addition, the synthesis can take place in the molten material or in a suitable solvent, which can be added before or during the preparation of the prepolymer. Suitable solvents are, for example, acetone, 2-butanone, tetrahydrofuran, dioxane, dimethylformamide, N-methyl-2-pyrrolidone

(NMP), ethyl acetate, alkyl ethers of ethylene and propylene glycol and aromatic hydrocarbons. The use of ethyl acetate as a solvent is particularly preferred.

[0148] Suitable examples of urethane (meth) acrylates include 7,7,9-trimethyl-4,13-dioxo-3,14-dioxa-5,12-diaza-hexadecane-1,16-dioxo-dimethacrylate (for example , Plex 666-1, Röhm), 7,7,9-trimethyl-4,13-dioxo-5,12-diaza-hexadecane- 1,16-dioxy-dimethacrylate (UDMA), urethane (methacrylates) derived from 1,4 and 1,3-Bis (1-isocyanate-1-methylethyl) bezene (for example, as described in EP 0934926 A1) and mixtures thereof.

[0149] According to one embodiment, urethane (meth) acrylate is characterized as follows: - it has structure A - (- S1-U-S2-MA) n, with - A being a connector element comprising at least one unit, - S1 being a spacer group comprising at least 4 units connected to each other, - S2 being a spacer group comprising at least 4 units connected to each other, - the units of A, S1 and S2 being selected independently from among CH3-, -CH2-, -O-, -S-, -NR1-, -CO-, -CR1 =, CC R1 CCN

N,,,,, -N =, -CR1R2-, with R1 and R2 being independently selected from hydrogen, alkyl, substituted alkyl, alkenyl, cycloalkyl, substituted cycloalkyl, arylalkyl, aryl or substituted aryl, and these units can form structures linear, branched or cyclic, such as alkyl, cycloalkyl, aryl, ester, urethane or amide groups, - U being a urethane group that connects the spacer groups S1 and S2, - MA being an acrylate or methacrylate group, and

- n being 3 to 6.

[0150] According to one embodiment, urethane (meth) acrylate is represented by structure A - (- S1-U-S2-MA) n with - A being a connector element comprising at least about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20 units, - S1 being a spacer group comprised of units connected to each other and comprising at least about 4, 5, 6, 7, 8, 9 or 10 units, - S2 being a spacer group comprised of units connected to each other and comprising at least about 4, 5, 6, 7, 8, 9, 10, 12, 15, 20 or 25 units, - U being a urethane group that connects the spacer groups S1 and S2, - MA being an acrylate or methacrylate group, and - n being 3 to 6, or from 4 to 6, or 5 to 6.

[0151] This may be preferable, if A has a cyclic structure and comprises at least about 6 units.

[0152] This may still be preferable if S1 has a linear or branched structure and comprises at least about 4 or about 6 units.

[0153] This may still be preferable if S2 has a linear or branched structure and comprises at least about 6 or about 8 units.

[0154] Urethane (meth) acrylate may also be preferred where A has a cyclic structure and comprises at least about 6 units, and S1 has a linear structure and comprises at least about 4 units, and S2 has a structure linear and comprises at least about 8 units, and U is a urethane group.

[0155] None of the atoms of the urethane group connecting S1 or S2 or the atoms of the (meth) acrylic group belong to the spacer group S1 or S2. Thus, the atoms of the urethane group do not count as units of the spacer groups S1 or S2.

[0156] The nature and structure of the connector element are not particularly limited. The connector element can contain saturated (no double bonds) or unsaturated (at least one or two double bonds), aromatic or heteroaromatic units (aromatic structure containing atoms including N, O and S).

[0157] Specific examples of connector element A having a cyclic structure include:

The N N N N O

O N O O N O (6 units) (6 units)

[0158] Specific examples of connector element A having a non-cyclic but branched structure include:

O O N N N

H H N (5 units) (1 unit)

HN The NH THE THE THE N AT THE H H O O N THE NH O

N O (16 units) H (15 units)

THE O O H The N N O N N O H H H O O O O O

HN HN (12 units) (15

The NH THE H H N O O N O O O THE

N units) H (17 units)

THE THE HN NH H N N N N O HN O H O THE N

H (10 units) (13 units)

THE NH The NH N N HN O

HN O (16 units)

[0159] The dotted lines indicate the connections to the spacer group S1.

[0160] The nature and structure of the spacer groups S1 or S2 are also not particularly limited.

[0161] Spacer groups are comprised of units connected with each other. Typical units include: CH3-, -CH2-, -O-, -S-, -NR1-, -CO-, - CR1 =, C C R1 C C N

N,,,,, -N =, -CR1R2-, with R1 and R2 independently selected from hydrogen, alkyl, substituted alkyl. alkenyl, cycloalkyl, substituted cycloalkyl, arylalkyl, aryl or substituted aryl.

[0162] These units can form linear, branched or cyclic structures, such as alkyl, cycloalkyl, aryl, ester, urethane or amide groups.

[0163] The structure of S1 can be identical to the structure of S2. However, in some modalities, the structure of S1 is different from S2. In a specific modality, the number of units present in S1 is less than or equal to the number of units present in S2.

[0164] In a specific modality, S1 may have a saturated hydrocarbon structure.

[0165] In another specific modality, S2 may have a saturated hydrocarbon structure.

[0166] Typical examples of spacer groups useful for S1 include: A C 4 U A C 6 U A C 8

U H2 H2 H2 (4 units) (6 units) (8 units)

A C U A C U H2 H2 (13 units) (13

A C H2

A C C U C U H2 H2 H2 units) (8 units) (8 units)

[0167] The dotted lines indicate the chemical bond to group A or to group U.

[0168] Typical examples of spacer groups useful for S2 include:

THE

MA U O (9 units)

THE

MA U O 2 (16 units)

THE

MA O U (6 units)

[0169] The dotted lines indicate the chemical bond to the (meth) acrylate group or to the U group. The number of units to be counted according to the invention is given in brackets.

[0170] Specific examples of curable component (B) include:

O O O O O

O O O 5 O N 6N N 6 N O 5 O

H H O O O N O

O O O N 6 O 5 H

O O O O O O O

O O O 5 2 O N 6N N 6 N O 5 2 O

H H O O O N O

O O O N 6 O 5 2 H

O O O O

O O O N 6 N O 5 O

H

O O O 5 O N 6 N O

H THE O N O

O O O N 6 O 5 H

O O O O O O O

O O O N 6N N 6 N O

H H O O O N O

O O N 6

The H O O O O O O O O

O O O 5 O N N6 N N 6 N O 5 O

OH OH

O O O 6 O 5 O N

H THE

[0171] Suitable additional (meth) urethane acrylates are based on α, ω-terminated poly (meth) acrylododiols (as described in EP 1 242 493 B1) or can be a polyester, polyether, polybutadiene or (meth) acrylate polycarbonate urethane (for example, as described in US patent 6,936,642 B2).

[0172] Urethane (meth) acrylate is typically present in the following amounts: - Lower amount: at least 1, at least 3 or at least 5% by weight; - Higher quantity: maximum of 35, maximum of 30 or maximum of 25% by weight;

- Range: 1 to 35 or 3 to 30 or 5 to 25% by weight; % by weight with respect to the weight of the polymerizable composition.

[0173] If the amount of urethane (meth) acrylate is too high, the resulting material can become very flexible and is unlikely to maintain its desired shape.

[0174] If the amount of urethane (meth) acrylate is too low, the resulting material can become very brittle. Fracture and impact resistance work can be negatively affected.

[0175] The curable composition described in this text comprises a filling matrix.

[0176] The filler matrix is typically present in an amount of 5 to 45% by weight or 10 to 40% by weight.

[0177] The amount of filler used can have an impact on the viscosity of the curable composition, the abrasion resistance of the cured composition or both.

[0178] The filler matrix may comprise pyrolyzed silica.

[0179] The specific surface of hydrophobic pyrolyzed silica is typically 100 to 300 or 150 to 250 m2 / g.

[0180] The mixture of different pyrolyzed silicas can be used, if desired. For example, a mixture of pyrolyzed silica whose surface has been treated with a hydrophobic surface treatment agent and pyrolyzed silica, whose surface has been treated with a hydrophilic surface treatment agent, can be used.

[0181] Suitable hydrophobic surface treatment agents include: - OSiR3, with R being selected from C1-4 alkyl, preferably methyl and mixtures thereof.

[0182] Hydrophobic pyrolyzed silica is also commercially available under the trade names HDK, in particular HDK-H ™ 2000 (Wacker) or Aerosil ™ R812 (Evonik).

[0183] It has been found that the use of pyrolysed silica whose surface has been treated with surface treatment agents containing polymerizable portions, such as (meth) acrylsilanes, can sometimes lead to an unwanted thickening of the curable composition, which can make the curable composition less suitable as processing material in an additive manufacturing process.

[0184] Accordingly, according to one embodiment, the curable composition described in this text does not typically contain pyrolysed silica with its surface treated with surface treatment agents containing polymerizable portions such as (meth) acrylsilanes, in an amount of more than 2% by weight or more than 1.5% by weight, or more than 1% by weight.

[0185] If present, pyrolyzed silica is typically present in the following amounts.

- Lower quantity: at least 0.5 or at least 1 or at least 1.5% by weight; - Higher quantity: maximum of 8, maximum of 7 or maximum of 5% by weight; - Range: 0.5 to 8 or 1 to 7 or 1.5 to 5% by weight; % by weight with respect to the weight of the entire curable composition.

[0186] The filling matrix comprises nano-cluster (s). One or more different types of nanoaggregation (s) may be present.

[0187] It has been found that, compared to other fillers, the use of nanoaggregation (s) is beneficial because it allows the formulation of a composition with a high filler load, resulting in better mechanical properties, for example, polishing or abrasion capacity and in better aesthetics.

[0188] The nanoaggregation can typically be characterized by at least one of the following resources: - Specific surface: from 30 to 400, or from 60 to 300, or from 80 to 250 m2 / g, - comprises particles of SiO2, ZrO2, Al2O3 and their mixtures.

[0189] If desired, the specific surface can be determined according to BET (Brunauer, Emmet and Teller) using a device (Monosorb ™) available from Quantachrome.

[0190] If desired, the average particle size can be determined by scattering light using, for example, a Malvern Mastersizer 2000 device available from Malvern Instruments.

[0191] A suitable nano-filling comprising nanodimensioned aggregate particles can be produced according to the processes described, for example, in US patent 6,730,156 (preparatory example A).

[0192] A useful nano-filling comprising aggregated nanoparticles can be prepared from a suitable sol and one or more solution (s) of heavy metal compound containing oxygen, which can be salts, sols, solutions or nanoparticles; of these materials, suns are preferred. For the purposes of this invention, a sol is defined as a stable dispersion of solid colloidal particles in a liquid. Solid particles are typically denser than the surrounding liquid and small enough that dispersion forces are greater than the gravitational force. In addition, the particles are small enough so that there is usually no visible light refraction. The careful choice of precursor suns results in a desired degree of visual opacity, strength, etc. The factors that will determine the choice of suns will depend on the combination of the following properties: a) the average size of the individual particles, which is preferably less than 100 nm in diameter, b) the acidity: the pH of the sun should be preferably below 6 and more preferably below 4, and c) the sun should be free of impurities that cause undue aggregation (during the filling preparation process) of the individual particles, during subsequent steps, such as drying or atomization calcination, in larger particles that cannot be easily dispersed or replaced and, therefore, decrease the translucency and polishing capacity of a dental restoration produced from a composite comprising these nanoparticles.

[0193] If the starting sol is basic, it must be acidified, for example, by adding nitric acid or another suitable acid to lower the pH. However, choosing a basic starting sun is less desirable as it requires an additional step and can lead to the introduction of unwanted impurities. Typical impurities that are preferably avoided are metal salts, particularly alkali metal salts, for example, sodium.

[0194] The non-heavy metal sol and the heavy metal oxide precursors are mixed together, preferably in a molar ratio to correspond with the refractive index of the hardenable resin. This gives a low and desirable visual opacity. Preferably, the molar ratio between non-heavy metal oxide (non-HMO, "non-heavy metal oxide") and heavy metal oxide (HMO, "heavy metal oxide"), expressed as non-HMO: HMO, is 0.5: 1 to 10: 1, more preferably, from 3: 1 to 9: 1, and most preferably, from 4: 1 to 7: 1.

[0195] In a preferred embodiment in which the nanodimensioned aggregate particles contain compounds containing silica and zirconium, the method of preparation begins with a mixture of silica sol and zirconyl acetate, in a molar ratio of about 5.5: 1.

[0196] Before mixing the non-heavy metal oxide sol with the heavy metal oxide precursor, the pH of the non-heavy metal oxide sol is preferably reduced to provide an acid solution with a pH of 1, 5 to 4.0.

[0197] The non-heavy metal oxide sol is then slowly mixed with the solution containing the heavy metal oxide precursor and vigorously stirred. Vigorous stirring is preferably carried out throughout the mixing process. The solution is then dried to remove water and other volatile components. Drying can be done in several ways, including, for example, tray drying, fluidized bed and spray drying. In the preferred method in which zirconyl acetate is used, drying is by spraying.

[0198] The resulting dry material is preferably composed of small substantially spherical particles as well as hollow sphere fragments.

These fragments are then calcined in batches for additional removal of organic residues. The removal of organic residues allows the filling to become more brittle, which results in a more efficient reduction in particle size. During calcination, the immersion temperature is preferably set to 200 ° C to 800 ° C, more preferably 300 ° C to 600 ° C. The immersion is done for 0.5 hour to 8 hours, depending on the amount of material to be calcined. It is preferred that the landing time of the calcination step is such that a plateau surface area is obtained. It is preferred that the time and temperature are chosen so that the resulting filler is white and free from black, gray or amber colored particles, as determined by visual inspection.

[0199] The calcined material is then preferably milled to an average particle size of less than 5 µm, preferably less than 2 µm (on a volumetric basis), as can be determined using a Sedigraph 5100 ( Micrometrics, Norcross, GA, USA). The determination of the particle size can be done by first obtaining the specific density of the filling using an Accuracy 1330 picometer (Micrometrics, Norcross, Ga., USA). The grinding can be carried out by various methods including, for example, agitation, grinding, vibrating grinding, fluid energy grinding, jet grinding, and ball grinding. Ball milling is the preferred method.

[0200] The resulting fillers comprise, contain, essentially consist of or consist of nanodimensioned aggregate particles. If desired, this can be tested by transmission electron microscopy.

[0201] If desired, the surface of the filler particles can be treated with surface treatment. The surface treatment can be carried out according to a process as described in US 6,730,156 (Windisch et al.) Or US 6,730,156 (Wu et al.). The content of these references is hereby incorporated by reference.

[0202] Once dispersed in the resin, the filling remains in an aggregate stage. That is, during the dispersion stage, the particles do not decompose into separate (that is, individual) and non-associated (that is, non-aggregated) particles.

[0203] If present, the nano-agglomerate (s) will typically be present in the following quantities: - Less quantity: at least 5, at least 10 or at least 15% by weight; - Greater quantity: maximum of 40, maximum of 38 or maximum of 35% by weight; - Range: 5 to 40 or 10 to 38 or 15 to 35% by weight; % by weight with respect to the weight of the entire curable composition.

[0204] The curable composition can also comprise particles visible on the X-ray.

[0205] The addition of particles visible on the X-ray to the dental composition is beneficial because it allows the dental professional to better identify the material placed in a patient's mouth and be able to distinguish between the dental structure of the healthy tooth and the artificial material. The material becomes radiopaque.

[0206] Particles visible on X-rays include particles of metal oxides and metal fluorides. Oxides or fluorides of heavy metals that have an atomic number greater than about 28 may be preferred. The heavy metal oxide or fluoride can be chosen in such a way that shading or undesired colors are not imparted to the tempered resin in which it is dispersed. For example, iron and cobalt would not be favored, as they impart contrasting and dark colors to the neutral tooth color of dental material. Most preferably, heavy metal oxide or fluoride is a metal oxide or fluoride that has an atomic number greater than 30. Suitable metal oxides are the oxides of elements of yttrium, strontium, barium, zirconium, hafnium, niobium, tantalum, tungsten, bismuth, molybdenum, tin, zinc, lanthanide (that is, elements that have atomic numbers in the range 57 to 71, inclusive), cerium and combinations thereof. Suitable metal fluorides are, for example, yttrium trifluoride and ytterbium trifluoride. Most preferably, heavy metal oxides and fluorides that have an atomic number greater than 30 but less than 72, are optionally included in the materials of the invention. Particularly, the preferred radiopacifying metal oxides include lanthanum oxide, zirconium oxide, yttrium oxide, ytterbium oxide, barium oxide, strontium oxide, cerium oxide and combinations thereof. Other suitable fillers to increase radiopacity are barium and strontium salts, especially strontium sulfate and barium sulfate.

[0207] The surface of heavy metal oxide or metal fluoride particles can be treated. If present, X-ray visible particles are typically present in an amount of 0.1 to 20, or 1 to 15, or 2 to 10%, by weight, with respect to the weight of the total composition. The curable composition described in the present text comprises an initiator system. The initiator system is typically present in an amount of 0.1 to 5 or 0.2 to 4 or 0.5 to 3% by weight. The initiator system comprises a photoinitiator and an organic dye.

[0208] The initiator system contributes to an efficient curing of the curable composition and controls the penetration and dispersion of light, and therefore can have an impact on the mechanical and aesthetic properties.

[0209] In certain embodiments, the photoinitiator (s) can be characterized by at least one or more, and sometimes all of the following parameters: ● show a radiation absorption band within a 200 to 500 or 300 to 450 nm range; ● be slightly yellow in color.

[0210] The photoinitiator must be able to start or initiate the curing or curing reaction of the radiation-curable component (s) that are present in the curable composition.

[0211] The photoinitiator typically shows a light absorption band in a wavelength range of 300 to 450 nm, preferably in the range of 350 to 420 nm. Suitable examples of photoinitiators typically contain a portion of phosphine oxide.

[0212] Examples of light curing initiator components include the acylphosphine oxide class, as described, for example, in US

4,737,593 (Elrich et al.)

[0213] Such acylphosphine oxides have the following general formula: (R9) 2  P (= O)  C (= O) —R10 each R9 individually being a hydrocarbyl group such as alkyl, cycloalkyl, aryl and aralkyl, either of which can be substituted with a halo-, alkyl- or alkoxy- group or the two R9 groups can be joined to form a ring together with the phosphorous atom, and where R10 is a hydrocarbyl group, a heterocyclic group of five or six members containing S-, O- or N-, or a group - ZC (= O) -P (= O) - (R9) 2, where Z represents a divalent hydrocarbyl group such as alkylene or phenylene having 2 to 6 atoms of carbon.

[0214] Preferred acylphosphine oxides are those in which groups

R9 and R10 are phenyl or phenyl substituted by lower alkyl or lower alkoxy. By "lower alkyl" and "lower alkoxy" is meant those groups having 1 to 4 carbon atoms.

[0215] Tertiary amine-based reducing agents can be used in combination with an acylphosphine oxide. Illustrative tertiary amines include ethyl 4- (N, N-dimethylamino) benzoate and ethyl N, N-dimethylamino (meth) acrylate.

[0216] Commercially available phosphine oxide photoinitiators capable of initiating reaction via free radical when irradiated at wavelengths greater than 400 nm to 1,200 nm include a 25:75 mixture, by weight, of bis (2,6- dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine and 2-hydroxy-2-methyl-1-phenylpropan-1-one (formerly known as IRGACURE ™ 1700, with Ciba Specialty Chemicals), 2-benzyl-2- (N, N-dimethylamino) -1- (4-morpholinophenyl) -1-butanone (formerly known as IRGACURE ™ 369, with Ciba Specialty Chemicals), bis (η5-2,4-cyclopentadien- 1-yl) -bis (2, 6-difluoro-3- (1H-pyrrol-1-yl) phenyl) titanium (formerly known as IRGACURE ™ 784 DC, with Ciba Specialty Chemicals), a 1: 1 mixture, by weight, of bis (2, 4,6-trimethylbenzoyl) phenylphosphine and 2-hydroxy-2-methyl-1-phenylpropan-1-one (formerly known as DAROCUR ™ 4265, available from Ciba Specialty Chemicals) and ethyl-2,4,6-trimethylbenzylphenyl phosphinate (LUCIRIN ™ LR8893X, with BAS F Corp., Charlotte, NC, USA) and 2,4,6-trimethylbenzoyldiphenylphosphine oxide (LUCIRIN ™ TPO).

[0217] Exemplary UV initiators include 1-hydroxy-cyclohexyl-benzophenone (available, for example, under the trade name “IRGACURE 184” from Ciba Specialty Chemicals Corp., Tarrytown, NY, USA), 4- (2-hydroxyethoxy ) phenyl- (2-hydroxy-2-propyl) ketone (available, for example, under the trade name “IRGACURE 2529” from Ciba Specialty Chemicals Corp.), 2-hydroxy-2-methylpropiophenone (available, for example, under the trade name “DAROCURE D111” with Ciba Specialty Chemicals Corp. and bis (2,4,6-trimethylbenzoyl) oxide -

phenylphosphine (formerly known as “IRGACURE 819” with Ciba Specialty Chemicals Corp.). The most preferred acylphosphine oxide is bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide (OMNIRAD ™ 819, IGM B.V. resin, Waalwijk, NL).

[0218] The photoinitiator (s) is present in the following quantity (s): - Lower quantity: at least 0.01, at least 0.05 or at least 0.1% by weight; - Higher quantity: at least 3, at least 2 or at least 1.5% by weight; - Range: 0.01 to 3 or 0.05 to 2% by weight or 0.1 to 1.5% by weight; percentage by weight with respect to the weight of the entire composition.

[0219] The polymerizable composition described in this text also comprises one or more organic dye (s).

[0220] The nature and structure of the organic dye (s) is not particularly limited, unless the desired result cannot be achieved.

[0221] It has been found that by adding an organic dye, the ability of the polymerizable composition described in the present text to absorb radiation can be improved.

[0222] In addition, it has been found that the addition of an organic dye contributes to suppress or reduce the transmission of scattered light in a polymerizable composition. This often helps to improve the precision or resolution of details of the surface of the three-dimensional article obtained from the additive manufacturing process.

[0223] In certain embodiments, the organic dye (s) can be characterized by at least one or more of all of the following parameters: a) have a light absorption band within a wavelength range from 350 to 420 nm; b) not having a light absorption band in the wavelength range of 400 to 800 nm; c) comprising a terephthalate portion.

[0224] The combination of parameters a) and b) is sometimes preferred.

[0225] Organic dyes that can be used include those containing a selected portion of the terephthalate groups and / or aromatic (hetero) cycles or other systems with the delocalized pi electrons. In particular, dyes useful for coloring food have been found to be useful.

[0226] The dye (s) that can be used include (s) Lumilux ™ Blue dye, Lumilux ™ Yellow dye (Honeywell) and mixtures thereof.

[0227] If present, the organic dye (s) is present in the following quantities: - Less quantity: at least 0.001, at least 0.002 or at least 0.005% by weight; - Higher quantity: maximum 0.5, maximum 0.2 or maximum 0.1% by weight; - Range: 0.001 to 0.5, 0.002 to 0.2 or 0.005 to 0.1% by weight; percentage by weight with respect to the weight of the entire composition.

[0228] The curable composition described in this text can also comprise one or more additive (s).

[0229] The additive (s) includes stabilizer (s), pigment (s) and mixtures thereof.

[0230] There is no need for any additives to be present, so no additives can be present. However, if present, they are typically present in an amount that is not detrimental to the intended purpose.

[0231] According to one embodiment, the curable composition comprises one or more stabilizer (s).

[0232] The nature and structure of the stabilizer (s) are not particularly limited, unless the desired result cannot be achieved.

[0233] A stabilizer can extend the life of the polymerizable composition, help prevent unwanted side reactions and adjust the polymerization process of the radiation-curable component (s) present in the curable composition.

[0234] The addition of one or more stabilizer (s) to the polymerizable composition can additionally help to improve the precision or resolution of details of the surface of the article to be produced.

[0235] In particular, it has been found that the addition of stabilizer (s) to the polymerizable composition described in this text can help to improve the resolution and accuracy of the SLA process by attenuation or avoiding the unwanted dispersion effects.

[0236] Stabilizer (s) that can be added include free radical scavengers such as substituted and / or unsubstituted hydroxy aromatics (eg, butylated hydroxytoluene (Ionol), hydroquinone, hydroquinone monomethyl ether (MEHQ), 3,5-di-tert-butyl-4-hydroxyanisole (2,6-di-tert-butyl-4-ethoxyphenol), 2,6-di-tert-butyl-4- (dimethylamino) -methylphenol or 2,5 -di-tert-butylhydroquinone, 2-hydroxy-4-methoxybenzophenone (UV-9), 2-hydroxy-4-n-octoxybenzophenone, phenothiazine, p-methoxyphenol (MOP), radical 2,2,6,6- tetramethyl-piperidine-1-oxyl (TEMPO) and HALS (hindered amine photostabilizers) and mixtures thereof.

[0237] If present, the stabilizer (s) are present in the following quantities.

- Lower quantity: at least 0.001, at least 0.002 or at least 0.005% by weight; - Higher quantity: maximum 0.5, maximum 0.2 or maximum 0.1% by weight; - Range: 0.001 to 0.5 or 0.002 to 0.2 or 0.005 to 0.1% by weight; % by weight with respect to the weight of the curable composition.

[0238] The adhesive composition described in this text can also comprise pigment (s).

[0239] If the curable composition is to be used in the dental or dental field, the pigment (s) should not negatively affect the aesthetics of the cured material.

[0240] Ideally, the cured composition should be the tooth color, for example, match with a color from the Vita ™ tooth color guide.

[0241] Pigment (s) that may be present include (s) titanium oxides, iron and mixtures thereof.

[0242] If present (s), the pigment (s) is present in the following quantities: - Less quantity: at least 0.001, at least 0.005 or at least 0.01 % by weight; - Higher quantity: maximum 0.02, maximum 0.05 or maximum 0.5% by weight; - Range: 0.001 to 0.5 or 0.005 to 0.05% by weight; % by weight with respect to the weight of the curable composition.

[0243] The curable composition described in this text does not contain fabric softener (s) in an amount above 5% by weight or above 3% by weight in relation to the weight of the entire composition.

[0244] During an autoclaving process, softeners can migrate from the cured composition. This can have a negative impact on the desired properties of the cured composition.

[0245] Additionally, the curable composition described in this text typically also does not contain pyrolyzed silica, the surface of which has been treated with hydrophilic and / or polymerizable silanes in an amount that can adversely affect viscosity and / or printability. The amount of pyrolyzed silica whose surface has been treated with polymerizable silanes is typically not greater than 2% by weight, 1.5% by weight or 1% by weight relative to the total weight of the composition.

[0246] The curable composition described in this text can be produced by combining and mixing the components of the composition. If desired, a high speed mixer can be used.

[0247] Typically, the radiation curable components are provided first and the other components are added to this.

[0248] Due to the presence of a photoinitiator, the production process is typically carried out under low light conditions.

[0249] During storage, the composition described in this text is typically packaged in a suitable packaging device.

[0250] The curable composition described in this text is typically stored in a container. Suitable containers include vases, foil pouches and cartridges, among others.

[0251] The volume of the respective containers is not particularly limited, but is typically in the range of 10 to 200,000 ml or from 500 to 10,000 ml.

[0252] The curable composition described in this text can also be provided as a kit of parts comprising the curable composition and an instruction for use.

[0253] The instructions for use typically describe the conditions under which the curable composition is to be used.

[0254] The invention also relates to a cured article obtainable or obtained by curing the curable composition described in the present text.

[0255] As the cured article is based on curing the curable composition described in this text, the cured article has basically or essentially the same chemical composition.

[0256] The cured article typically has the following properties, alone or in combination: - flexural strength: 50 to 200 MPa or 80 to 150 MPa, determined in accordance with ISO 4049: 2009, using a test bar with the dimensions 6 * 4 * 25 mm, while 6 mm is the width of the test bar; - Module E from 1,000 to 4,000 MPa, determined according to DIN EN 843-2: 2007, using the flexural strength method, while the module calculation is made in the range of 20% to 50% of the maximum strength of the samples; - impact resistance: 5 to 15 kJ / m2, determined according to DIN 53453: 175-05; - abrasion: less than 20, less than 15 or less than 10 mm3 (determined as described in the examples section); - being autoclavable without a significant change (for example, +/- 10%) of the mechanical properties; - has tooth color.

[0257] The combination of the features presented below is often preferred: high impact resistance combined with low abrasion.

[0258] Sufficient flexural strength is beneficial because the crown material does not break easily.

[0259] A sufficiently low E modulus is beneficial because the crown material has sufficient flexibility.

[0260] Sufficient impact resistance is beneficial because the crown material has a high toughness and can withstand fracture.

[0261] Sufficient abrasion is beneficial because the crown will not soften and will maintain its anatomical shape during chewing. According to one embodiment, the cured article is a dental article.

[0262] Dental articles can have different shapes, such as the shape of a crown, bridge, filling, restoration, veneer, dental table top or parts thereof. A table top refers to a crown preparation in which only the upper part (that is, the chewing surface) of the crown is prepared.

A table top is sometimes also called an “occlusion plug”.

[0263] According to a preferred embodiment, the dental article is shaped like a preformed dental composite crown. The shape of a dental composite crown is typically characterized as follows:

[0264] The preformed crown has a top surface and dependent buccal surfaces, respectively labial, mesial, distal, lingual, respectively palatal lateral surfaces.

[0265] The lateral surfaces are connected to each other and form a neck of the crown. The lower region of the crown neck forms the border of the crown or the edge of the crown.

[0266] The preformed dental composite crown has an outer surface and an inner surface. The inner surface is the surface to be attached to a prepared tooth.

[0267] The thickness of the pre-formed crown wall on the crown neck (at a distance of 1 mm from the crown margin) is equal to or less than 0.8, equal to or less than 0.7 or equal to or less than 0 , 6 mm or is in a range of 0.1 to 0.8 mm, or 0.1 to 0.7 mm, 0.1 to 0.6 mm or 0.1 to 0.5 mm.

[0268] The wall thickness of the top surface (occlusal and / or distal) of the preformed crown is typically in the range of 0.15 mm to 1.5 mm or in the range of 0.4 mm to 1.0 mm .

[0269] At least two of the opposite and dependent lateral surfaces of the preformed composite crown have a concave shape, preferably the buccal and lingual lateral surfaces. That is, the side walls of the preformed crown have a curved shape and, thus, provide a recess in the region of the crown neck.

[0270] If desired, the dimension of the recess U in mm can be calculated using the formula U = D2 - D1, where D1 is the distance from the opposite inner side walls with a concave shape of the preformed crown measured 1 mm above the crown neck, if the preformed crown is cut in halves, and where D2 is the maximum distance from said internal opposite side walls of the crown measured parallel to D1.

[0271] In one embodiment, the shape of the preformed dental composite crown is additionally characterized by one of the following characteristics, alone or in combination:

[0272] The wall thickness of the side surfaces of the crown is typically not greater than 0.7 mm, 0.6 mm, 0.5 mm or 0.4 mm.

[0273] According to one embodiment, the wall thickness of the lateral surfaces of the preformed crown is in a range of 0.1 mm to 0.7 mm. According to another embodiment, the wall thickness of the lateral surfaces of the preformed crown is in a range of 0.1 mm to 0.6 mm. According to another embodiment, the wall thickness of the lateral surfaces of the preformed crown is in a range of 0.1 mm to 0.5 mm. According to another embodiment, the wall thickness of the lateral surfaces of the preformed crown is in a range of 0.1 mm to 0.4 mm.

[0274] Such format is described, for example, in the EP application under the EP number

16158959.3 (filed on March 7, 2016). The contents of this document are hereby incorporated by reference.

[0275] The preformed dental composite crown typically has two types of surfaces: an external surface being visible after fixing the dental article in a patient's mouth and an internal surface that becomes invisible after fixing the dental article in a patient's mouth .

[0276] According to one embodiment, the inner surface of the preformed dental composite crown is roughened (for example, by sandblasting) and / or has retaining elements. This feature can help improve the adhesion of the crown to the surface of a prepared tooth.

[0277] According to one embodiment, the outer surface of the preformed dental composite crown is polished.

[0278] During storage, the cured article is typically placed in a suitable packaging device.

[0279] Suitable packaging devices include sealed blister packs, plastic cases, trays or refill boxes.

[0280] The cured article described here can be obtained by polymerizing the curable composition described in this text.

[0281] Polymerization can be done by applying an additive manufacturing technique.

[0282] Such a technique is particularly useful if the production of individual articles is desired.

[0283] The polymerizable composition described in this text can be processed as a building material in an additive manufacturing process, in particular in a stereolithography (SLA) process.

[0284] According to one embodiment, the additive manufacturing process comprises the steps of ● providing a layer of the building material on a surface, ● radiation curing the parts of the building material layer that belong to the 3-dim article to be produced,

● provide an additional layer of construction material in contact with the radiation-cured surface of the previous layer, ● repeat the previous steps until a 3-dim article is obtained.

[0285] This process comprises the step of applying radiation to the surface of a radiation-curable material, in which the radiation is applied only to the parts of the surface that will later form a part of the article to be produced.

[0286] Radiation can be applied, for example, using a laser beam or by projecting a mask image. Using a stereolithographic process based on mask image projection (MIP-SL) is sometimes preferred, as it allows for faster fabrication of the article.

[0287] A MIP-SL process can be described as follows: i. A three-dimensional digital model of the article to be produced is provided.

ii. The three-dimensional digital model is cut by a set of horizontal planes.

iii. Each thin slice is converted into a two-dimensional mask image.

iv. The mask image is then projected with the aid of a radiation source on the surface of the radiation-curable material located on a construction platform (for example, which is shaped like a vat).

v. Radiation-curable material is cured only in those regions that are exposed.

saw. The construction platform containing the radiation-curable material or the layer of cured material is moved in relation to the radiation source, a new layer of radiation-curable material is provided being in contact with the layer of cured material produced in the previous step .

vii. Steps (iv) to (vi) are repeated until the desired article is formed.

[0288] The projection of the mask image on the radiation curable material can be done from top to bottom or from bottom to top in relation to the orientation of the bowl. Using the technique from the bottom up can be beneficial, as less radiation-curable material is needed.

[0289] In this process, the layer cured by radiation is formed at the bottom of the vat, which is transparent.

[0290] The polymerizable composition described in this text has been found to be particularly useful for processing it in a stereolithography process by projecting a mask image using the bottom-up projection technique.

[0291] Suitable process parameters for an SLA process include: - Radiation wavelength: 350 to 420 nm; - Curing time: 0.5 to 20 seconds; - Layer thickness: 1 to 100 µm.

[0292] After processing the curable composition to form a 3-dim article, the 3-dim article is typically removed from the device used to carry out the additive manufacturing process.

[0293] If desired, the surface of the 3-dim article is cleaned, for example, by rinsing the 3-dim article with a solvent.

[0294] Suitable solvents include low boiling alcohols, as described in this text (for example, an alcohol having a boiling point below 100 ° C; such as methanol, ethanol, n- or isopropanol) and mixtures of same or high-boiling solvents, as described in this text, preferably the same solvent (s) present in the sun, for example, diethylene glycol ethyl ether.

[0295] If desired, the 3-dim article can be further cured by applying radiation or heat. This step can help to improve the stability of the 3-dim article.

[0296] If applied, the post-cure stage can be characterized by at least one, or by all of the following characteristics: ● apply radiation with a wavelength of 350 to 450 nm; ● apply a heating step of 30 to 120 or 40 to 80 ° C.

[0297] Thus, a suitable process for processing the curable composition described in this text may comprise the following steps: a) providing a curable composition, as described in this text, b) producing a precursor of cured article with a 3d printer that has a radiation curable vat of the curable composition, the cured article having an outer surface and an inner surface, c) removing the precursor of the cured article from the 3d printer vat, d) cleaning the precursor of the cured article, e) subsequently cure the precursor of the cured article to obtain a cured article, f) optionally remove any support structures, if present g) optionally, polish at least parts of the outer surface of the cured article, h) optionally sandblast at least parts of the internal surface of the cured article.

[0298] If desired, step c) can also be performed after step d) or after step e).

[0299] According to one embodiment, the cured article is shaped like a preformed dental composite crown.

[0300] The precursor of the cured article can comprise supporting elements, which support and transport the precursor of the cured article during the 3d printing process. If they are present, the support elements are removed later in the process, for example, after step c), d) or e).

[0301] The invention also relates to a kit of parts comprising at least two cured articles described in this text, with cured articles having the shape of a dental crown.

[0302] A kit can comprise up to 200 or up to 150 differently shaped preformed dental composite crowns.

[0303] A kit can comprise each of the dental composite crowns preformed differently in an amount of up to 10 or up to 8 different sizes.

[0304] Preformed dental composite crowns can be shaped like an anterior tooth or a posterior tooth.

[0305] Typically, preformed dental composite crowns are supplied in different tooth colors. Tooth colors are typically classified according to the Vita ™ color code.

[0306] The invention also relates to a kit of parts comprising at least one cured article that has the shape of a dental article obtained by radiation curing of the curable composition described in this text and one or more of the following items: - cement dental, - instructions for use.

[0307] In this way, the kit of parts may also comprise a dental cement suitable for securely fixing the preformed dental composite crown to a prepared dental surface.

[0308] Suitable dental cementations are glass ionomer cement and, in particular, resin-modified glass ionomer cement. Typically, glass ionomer cements contain the following components: reactive acidic charge, polyacid, water and complexing agent, but no radiation-curable components.

[0309] Glass ionomer cement is typically supplied as a parts kit comprising a liquid part and a powder part. The two parts need to be mixed together before use.

[0310] The powdered part typically comprises an acidic reactive inorganic charge (for example, a fluorine aluminosilicate glass, FAS glass).

[0311] The liquid part typically comprises a polyacid, water and a complexing agent (for example, tartaric acid).

[0312] Glass ionomer cements are commercially available (for example, Ketac ™ Cem; from 3M Oral Care).

[0313] The glass ionomer cement can also be supplied as a kit of parts comprising two pastes A and B to be mixed before use.

[0314] According to a preferred modality, the kit of parts containing the preformed dental composite crowns comprises a resin-modified glass ionomer cement (RRM-GIZ).

[0315] Resin-modified glass ionomer cement typically contains the following components: reactive acidic charge, polyacid, water, complexing agent, radiation curable components, initiator.

[0316] Suitable radiation curable components typically contain portions of (meth) acrylate.

[0317] Resin-modified glass ionomer cases are supplied as a kit of parts as well, either as a powder / liquid or paste / paste system.

[0318] The powdered part typically comprises acidic reactive inorganic filler (s) (for example, fluoroaluminosilicate glass, FAS glass) and initiator components.

[0319] The liquid part typically comprises polyacid, water, (meth) acrylates and initiator components.

[0320] Resin-modified glass ionomer cement are commercially available (eg Ketac ™ Cem Plus; from 3M Oral Care).

[0321] It has surprisingly been found that, in particular, an RM-GIZ is suitable for securely attaching the preformed dental composite crown to the surface of a prepared tooth.

[0322] Although slightly more expensive than classic glass ionomer cement, RM-GIZ can be obtained at a lower cost compared to self-adhesive resin cement (eg RelyX ™ Unicem) or adhesive resin cement (for example, RelyX ™ Ultimate). 3M Oral Care).

[0323] According to one embodiment, the cured article described here has the shape of a dental article, and in particular, the shape of a preformed dental composite crown.

[0324] The preformed dental composite crown described in this text is used to treat a dental tooth, in particular, in the pediatric field.

[0325] Such a method comprises the step of fixing the preformed dental composite crown, as described in this text, to the surface of a tooth prepared in a patient's mouth using a dental cement, as described in this text, in particular, a resin-modified glass ionomer cement.

[0326] If desired, the surface of the preformed dental composite crown that must be attached to the surface of the prepared tooth ("inner surface") can be roughened before the dental cement is applied. Roughness can be achieved, for example, by sandblasting.

[0327] The roughness of the surface can also be useful to further improve the fixation of the preformed crown to the prepared surface of the tooth to be treated.

[0328] If desired, the shape of the preformed dental composite crown can be further adapted by cutting or sanding.

[0329] According to one embodiment, the curable composition, as described in this text, comprises: polymerizable (meth) acrylate (s) that does not comprise a portion of urethane comprising at least two portions of (met) ) acrylate, having a molecular weight of 170 to 3,000 g / mol and being present in an amount of 40 to 85% by weight, with the polymerizable urethane (meth) acrylate (s) comprising at least three portions of urethane, having a molecular weight of 450 to 3,000 g / mol and being present in an amount of 1 to 35% by weight, nano-cluster comprising particles based on Si or Zr, and being present in an amount of 5 to 40% by weight, optionally pyrolysed silica being present in an amount of 0.5 to 7% by weight, particles visible in X-rays being present in an amount from 0 to 15% by weight, photoinitiator comprising a portion of phosphine oxide , and being present in an amount of 0.01 to 3% by weight, the stabilizer being present in a the amount of 0.001 to 0.5% by weight, organic dye in an amount of 0.001 to 5% by weight, with the curable composition not comprising softener in an amount of more than 5% by weight, weight percentage with respect to weight of the entire composition.

[0330] All components used to produce the curable composition, and in particular the dental articles described in this text, must be sufficiently biocompatible, that is, the composition must not produce a toxic, harmful or immunological response in living tissue.

[0331] The complete disclosures of patents, patent documents and publications cited herein are incorporated by reference, in their entirety, as if each were individually incorporated. Various modifications and changes in the context of this invention will become apparent to those skilled in the art without departing from the character and scope of this invention.

The specification, examples and data above provide a description of the manufacture and use of the compositions and methods of the invention. The invention is not limited to the modalities disclosed herein. The person skilled in the art will recognize that many alternative modalities of the invention can be carried out without deviating from its character and scope.

[0332] The following examples are intended to illustrate the invention.

Examples

[0333] Unless otherwise noted, all parts and percentages are weight based, all water is deionized water and all molecular weights are weight average molecular weights. In addition, except where otherwise noted, all experiments were conducted under ambient conditions (23 ° C; 1013 mbar (101.3 kPa)).

Component B methods

[0334] Viscosity was measured using a Physica MCR 301 rheometer device, with a plate-to-plate system (diameter 15 mm) and a slit of 0.2 mm. Viscosity values (Pas) were recorded at 23 ° C for a shear rate of 1 s-1. Flexural strength

[0335] If desired, flexural strength can be determined by performing a three-point flexural strength test, according to ISO 4049: 2009, using a test sample that is 4 * in size 6 * 25 mm. The flexural strength is given in [MPa].

Module E

[0336] Module E was determined according to DIN EN 843-2: 2007 using a test bar with dimensions 6 * 4 * 25 mm, 6 mm being the sample width. Module E was determined between the range of 20% and 50% of the maximum strength of the test sample. Module E is given in [GPa].

Impact resistance

[0337] If desired, the impact resistance can be determined according to DIN 53453: 1975-05 (Charpy) using test samples that are 4 * 6 * 50 mm in size, using a Zwick 5102 pendulum mounted with a pendulum of 0.5 J and using an amplitude of 42 mm. Impact resistance is given in [kJ / m2].

Abrasion

[0338] If desired, the abrasion [mm3] can be determined as follows: Abrasion tests were carried out on specific samples with an angular coefficient of 30 °. For that purpose, the materials were filled in the depression of inbus screws (with hexagonal head) M12 and cured according to the manufacturer's instructions.

[0339] The samples were ground using a 75 µm diamond saw and stored in distilled water for 4 days at 36 ° C. Then, the chewing simulation started under the following conditions:

[0340] Chewing force: 80 N; Lateral movement: 4 mm; Sliding movement: 10 mm; Antagonist: soapstone ball; Number of masticatory cycles:

1,200,000; Thermocycles (5/55 ° C): 5,000.

[0341] After the mastication simulation, abrasion was determined by measuring the volume loss with the use of VK-X200 laser scanning microscopy (Keyence Company).

[0342] Additional information on the abrasion test can be found in M. Rosentritt et al., Materialprüfung 39 (1997), p. 77-80.

Printing capacity assessment

[0343] Two different print configurations were used, each containing at least 2 precursor articles on the printing platform:

[0344] Print configuration 1: the distance from the precursors of the article was 2 mm or less.

[0345] Print configuration 2: the distance from the precursors of the article was at least 3 mm.

[0346] The shortest distance between the precursors of the article allows the simultaneous printing of a greater number / volume of the articles on a given printing platform and, thus, a more efficient manufacturing process.

[0347] After the printing process, the precursors of the printed article were evaluated visually and classified as “YES”, if the geometric dimensions of the precursor of the printed article corresponded with the geometric dimensions of the respective STL file and “NO” if the dimensions geometries of the precursor of the printed article did not match the geometric dimensions of the respective STL file.

Materials

Nanoagomerate nanoparticles aggregated US 6,730,156 B1, Zr / Si column nano-clusters; filler 25, preparatory example A; the filler particles obtained had their surface treated in accordance with preparatory example B of US 6,730,156 B1. HDK ™ H-2000 pyrolyzed silica filler; surface modification: - OSi (CH3) 3; Aerosil ™ R711 agglomerated nanoparticles filling with pyrolyzed silica; surface modification: methacrylsilane SG-YBF100 ytterbium fluoride powder; filler D-Zetacrylate Bisphenol A dimethacrylate ethoxylate; DESMA polymerizable methacrylate (urethane methacrylate); EP 1 167 polymerizable methacrylate 013 B1 (p. 20) GDMA Glycerol dimethacrylate Ionol ™ 2,6-ditherc-butyl-4-methylphenol; stabilizer Z-Acetate Bisphenol A ethoxylated diacetate; TEGDMA softeners Lucirin ™ TPO triethylene glycol dimethacrylate Photoinitiator Ircacure ™ 819 Lumilux ™ Blau photoinitiator Organic dye

LZ Table 1

[0348] The compositions described in Table 2 have been prepared. The number of components is given in parts, by weight (pbw): Ex1 (EC) Ex2 (EC) Ex3 (EC) Lucirin TPO - - - Ircacure 819 - 0.54000 0.54000 Lumilux Blau LZ 0.00136 0.00136 0.00136 Cu-procetonate 0.00273 - - Amine-HCl 0.17273 - - Ionol 0.02727 0.02727 0.02727 D-Zetacrylate 39.96591 39.96727 39.96727

DESMA 4.37545 4.37545 4.37545 HDK H-2000 4.54545 4.54545 4.54545 SG-YBF 100 2.27273 2.27273 2.27273 Aerosil R711 1.81818 1.81818 1.81818 Zr nanoaggregation / Si 38.63636 38.63636 38.63636 TBPIN 0.02727 - - BZPBS 0.90909 - - Z-Acetate 7.24545 7.24545 - Ex4 (EC) Ex5 (EC) Ex6 (EC) Ex7 (EC) Lucirin TPO - 0.54000 0.54000 0.54000 Ircacure 819 0.54000 - - - Lumilux Blau LZ 0.00136 0.00136 0.00136 0.001492 Cu-procetonate - - - - Amine-HCl - - - - Ionol 0 , 02727 0.02727 0.02727 0.0497 D-Zetacrylate 39.96727 39.96727 39.96727 0.1477 GDMA - - - 29.7186 DESMA 4.37545 4.37545 4.37545 19.8124 HDK H-2000 4.54545 4.54545 1.70000 3.9794 SG-YBF 100 2.27273 2.27273 2.27273 2.4865 Aerosil R711 1.81818 1.81818 - 0.9946 Zr / Si nanoaggregation 18.20000 18, 20000 18.20000 42.2705 TBPIN - - - - BZPBS - - - - Z-Acetate - - - - Table 2 EC: Comparative Example; EI: Example of the Invention

[0349] The composition of Ex1 essentially corresponds to the composition described in Example 1 of WO 2015/006087 A1 and functions as a comparative example (EC).

[0350] In the composition of Ex2, the Exox redox initiator system was replaced by a photoinitiator system.

[0351] In the composition of Ex3, the softener component (Z acetate) was omitted.

[0352] In the composition of Ex4, the amount of the filler was reduced.

[0353] In the composition of Ex5, the photoinitiator system was changed.

[0354] In the composition of Ex6, the amount of silica treated with methacrylsilane was reduced.

[0355] The composition of Ex7 essentially corresponds to the composition described in example 3 of US 2016/0136059 A1 (Hecht et al.), Except that a photoinitiator system was used instead of a redox curing initiator system.

General processing of curable compositions

[0356] For the Ex1 curable compositions provided in Table 2, the components were supplied and mixed using a kneader in order to obtain homogeneous paste A and paste B. The pastes were placed in a double chamber cartridge with a volume of paste A to paste B of 10: 1 (SulzerMixpac). The composition was dispensed through a static mixing tip (SulzerMixpac) using a manually operated gear in molds with a geometry of 4 mm x 6 mm x 25 mm, removed after 1 h and stored in deionized water for 24 h.

[0357] For the curable compositions of Examples Ex2, Ex3, Ex4, Ex5 and Ex6, the components were supplied and mixed using a kneader to obtain a homogeneous paste. The paste was dumped into the working tray of a commercially available DLP printer (Rapidshape HA30; Heimsheim, Germany).

[0358] Pre-processing data (STL file; 3-dim format.

Object; 4 mm × 6 mm × 25 mm) were loaded in the printer.

[0359] The following processing conditions were used: - curing light wavelength: 383 nm light; - exposure time: 11 s; - layer thickness: 50 µm; - printing protocol: using the standard parameter defined for material GP101 (Software: Netfabb Professional for Rapidshape 5.2 64 bit).

[0360] The article precursors were finalized by applying the following steps: - removal of the article precursor from the construction platform - cleaning of the article precursor for 5 minutes in isopropanol using the ultrasonic device (Fa. BANDELIN electronic GmbH & Co. KG, DT 100 H) - light cure of the precursor article for 900 sec under argon conditions.

[0361] The cured articles obtained were tested for viscosity and printing properties, as described in Table 3. A viscosity above 150 Pa.s was considered too high for proper processing. Ex Ex1 Ex2 Ex3 4 Ex5 Ex6 Ex7 No Si Curability by radiation o Yes Yes m Yes Yes Yes Yes N.D No No No No No N.D Print configuration 1. o o oo Yes. N.D N.D N.D Si N.D N.D Print configuration 2. . . .m Yes. Viscosity in [Pas] at a shear rate of 18,1 [s-1] n.a. 217 357 195 202 2 268 Table 3 N.D. * Not determined

[0362] Additionally, the cured articles obtained were tested for mechanical properties, as described in Table 4 before and after carrying out a simulated autoclave process applying the following conditions: placing the cured article in an oven at 120 ° C for 24 h. Ex1 Ex4 Ex6 initial values Elastic module in Gpa 3.1 3.8 2.7 24 h, at 120 ° C Elastic module in Gpa 3.9 3.6 2.8 Delta in% Elastic module 20 -6 4

[0363] Due to the absence of a photoinitiator, the composition of Ex1 is not radiation curable and cannot be processed in an SLA process.

[0364] The Ex2 composition contained a photoinitiator and can therefore be processed in an SLA process.

[0365] However, the ability to print precursor articles using Print Configuration 1 was rated as unsatisfactory. The viscosity of the curable composition was very high.

[0366] The Ex3 composition contained a photoinitiator, but not a fabric softener. Like the composition of Ex2, the ability to print the precursor article was rated as unsatisfactory. The viscosity of the curable composition was very high.

[0367] The Ex4 composition that contained a lower amount of pool filler was used. The composition was classified as being autoclavable. In addition, the viscosity of the curable composition could be decreased, but the ability to print the precursor article using Print Configuration 1 has not yet been satisfactory.

[0368] The Ex5 composition contained a different photoinitiator. The printability and viscosity of the composition have not changed significantly.

[0369] In the composition of Ex6, the amount of silica filler was reduced. The viscosity of the curable composition decreased significantly. The printability using Print Configuration 1 was rated satisfactory. In addition, the cured composition was also cured as being autoclavable.

Claims (15)

1. Curable composition to produce dental composite crowns, CHARACTERIZED by the fact that the composition comprises a resin matrix comprising: polymerizable (meth) acrylate (s) that does not comprise (u) a portion of urethane, and ( met) polymerizable urethane acrylate (s), wherein the polymerizable (meth) acrylate (s) that do not comprise a portion of urethane is / are in excess of the ) (meth) polymerizable urethane acrylate (s), a filler matrix comprising: nanoaggregation (s), optionally pyrolysed silica in an amount below 8% by weight, where the filler matrix is present in a amount of 5 to 45% by weight, an initiator system comprising: photoinitiator (s), and organic dye (s); a softener in an amount of not more than 5% by weight, with the curable composition having a viscosity below 150 Pa.sa at 23 ° C and a shear rate of 1 s-1, and in which% by weight is related the total weight of the curable composition. 2. Curable composition, according to claim 1, CHARACTERIZED by the fact that the resin matrix is present in an amount of 40 to 85% by weight, the initiator system is present in an amount of 0.01 to 5% in weight, where% by weight is related to the weight of the curable composition. 3. Curable composition, according to claim 1 or 2, CHARACTERIZED by the fact that it has one or more of the following characteristics: curable by radiation having a wavelength in the range of 350 to 600 nm; viscosity: 1 to 100 Pa.s at 23 ° C at a shear rate of 1 s-1; and pH value: 6 to 8. 4. Curable composition according to any of claims 1 to 3, CHARACTERIZED by the fact that it comprises a pyrolyzed silica having one or more of the following characteristics: BET surface area: 100 to 300 m2 / g; and the surface being treated with an alkylsilane. 5. Curable composition according to any of claims 1 to 4, CHARACTERIZED by the fact that it comprises: polymerizable (meth) acrylate (s) that do not comprise a portion of urethane present in an amount of 40 to 85%, by weight, polymerizable urethane (meth) acrylate (s) present in an amount of 1 to 35%, by weight, nanoaggregation present in an amount of 5 to 40% by weight, pyrolysed silica present in an amount of 0 , 5 to 5% by weight, photoinitiator present in an amount of 0.01 to 3% by weight, organic dye present in an amount of 0.001 to 0.5% by weight. 6. Curable composition according to any one of claims 1 to 5, CHARACTERIZED by the fact that it comprises one or more of the following components: particles visible in X-rays present in an amount of 0.1 to 5% in stabilizing weight present in an amount of 0.001 to 0.5% by weight; and pigments present in an amount of 0.001 to 0.5% by weight; wherein% by weight is related to the weight of the curable composition. 7. Curable composition according to any of claims 1 to 6, CHARACTERIZED by the fact that it does not comprise one or more of the following components: redox initiator system; surface of pyrrolized silica treated with (meth) acrylate silanes in an amount of more than 2% by weight; and ceramic glass or glass particles in an amount of more than 5% by weight, where% by weight is related to the weight of the curable composition. 8. Curable composition according to any one of claims 1 to 7, CHARACTERIZED by the fact that it is as follows: polymerizable (meth) acrylate (s) that does not comprise a portion of urethane, comprising at least two portions of (meth) acrylate, having a molecular weight of 170 to 3,000 g / mol, and being present in an amount of 40 to 85% by weight, the polymerizable urethane (meth) acrylate (s) ( is), comprising at least three portions of urethane, having a molecular weight of 450 to 3,000 g / mol and being present in an amount of 1 to 35% by weight, nanoaggregation comprising particles based on Si or Zr, and being present in an amount of 5 to 40% by weight, optionally pyrolysed silica being present in an amount of 0.5 to 7% by weight, particles visible in X-rays being present in an amount of 0 to 15% by weight, photoinitiator comprising a portion of phosphine oxide, and being present in an amount of 0.01 to 3% by weight, stabilizer being present in an amount of 0.001 to 0.5% by weight, organic dye in a amount of 0.001 to 5% by weight, a softener in an amount of not more than 5% by weight, where% by weight is related to the weight of the curable composition. 9. Cured article CHARACTERIZED by the fact that it is obtained by radiation curing of the curable composition, as defined in any one of claims 1 to 8. 10. Cured article, according to claim 9, CHARACTERIZED by the fact that it has one or more of the following characteristics: flexural strength: 50 to 200 MPa, determined according to ISO 4049: 2009: Module E: 1,000 a 4,000 MPa, determined according to DIN EN 843-2: 2007; impact resistance: 5 to 15 kJ / m2, determined according to DIN 53453: 175-05; abrasion: less than 20 mm3; being autoclavable; and having tooth color. 11. Cured article, according to claim 9 or 10, CHARACTERIZED by the fact that it has the shape of a crown, bridge, filling, restoration, facet, dental table-top or parts thereof. 12. Kit of parts CHARACTERIZED by the fact that it comprises at least two cured articles, as defined in any of claims 9 to 11, cured articles having the shape of a dental crown and being different from one or more of the following characteristics: size; color; Format. 13. Kit of parts CHARACTERIZED by the fact that it comprises: at least one cured article, as defined in claim 9, the cured article having the shape of a dental crown, and one or more of the following: self-adhesive dental cement; and instructions for use. 14. Process for producing a cured article, as defined in any of claims 9 to 11, CHARACTERIZED by the fact that the process comprises Providing a curable composition, as defined in any of claims 1 to 8; and processing the curable composition by applying an additive manufacturing technique. 15. Process according to claim 14, CHARACTERIZED by the fact that the processing of the curable composition comprises: producing a precursor of the cured article with a 3d printer that has a vat, removing the precursor of the cured article from the 3d printer vat, cleaning the precursor of the cured article, subsequently curing the precursor of the cured article to obtain a cured article, and optionally polishing at least parts of the surface of the cured article.